Apparatus for the recovery of solvent



1945- G. E. DESETTI ET AL I 2,367,437

, APPARATUS FOR THE RECOVERY OF SOLVENTS Filed Dec. 11, 1942 GE Desetll' .Q 9W 3mm BIZ/Mickey. v R. G. Wbodbriaye k:

M www Patented Jan. 16, 1 945 APPARATUS FOR THE RECOVERY OF SOLVENT Gild E. Desetti, Woodbury, N.-J., and-Walter A.

Dew, Bill H. Mackey, and Richard G. Wood bridge, In, Wilmington, DeL, assignors to E. I. du-Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Original application May 14, 1941, Serial No. 393,340, new Patent No. 2,349,249, dated May 23, 1944. Divided and this application December 11:1942, Serial No. 468,684

2 Claims.

This invention pertains to the recovery of solvent from smokeless powder, particularly with respect to an improved apparatus for the recovery of said solvent.

addition are designed to be made airor gastight by means of the liquid seal (shown in Fig. 2). -,The drying medium is introduced into the car through opening 4. At this juncture, the line This application is a division of U. S. applica- 5 5 is joined to the car and the jointure also made 'tioh'Ser'ial No. 393,340, filed May 14, 1941. gas-tight by means of a liquid seal, After the The object of the present invention is an as,- powder-has been treated it is removed from the sembly adapted. to the efficient removal of solcontainer merely by opening up the hinged sec- Vent While Permitting the production of a subtion I and shoveling it therefrom, or by tilting stantially uniform powder. Another object is an 1 the car somewhat and permitting the powder to apparatus adapted to facilitate control of the flowf through said-opening. solvent vapor content of the drying medium dur- The direction of flow oi the drying medium ing the solvent recovery treatment, A further is indicated. It may be seen that the direction object is a solvent recovery assembly adapted'to of flow of the gas is ward y into the ca the regulated removal of solvent from smokeless said flow being distribute l m' t t ou t powder by controlling the solvent vapor content I the bulk of the powder in the container by means of the drying medium and the temperature of also shown in Fig. 2, the flow of the gas continusaid drying medium as well as that of the powder 1 i g on through the screen and exitin from being treated. A still further object is an apderneath the screen, where it passes to the filter, paratus capable of use for all the steps involved ThB p p between the filter and is in the finishing of powder, that is to say, solvent nected to said car. by meansoi' a removable vaporo y, water drying, and air drying. Other tight member, 6. The filter serves the purpose objects will become apparent as the inventio is of removing any finely divided solid particles described in detail hereinafter. which may pass through .the "screen and which The foregoing objects are attained by means 2 otherwise might cause damage to the assembly. of the assembly shown in the accompanying 'Although various filteri media y e c drawing which illustrates preferred embodiments p y We p e to use 81385 W because this of the invention. Figure 1 denotes a schematic at al has p oved to be particularly eflicacious plan ofthe various elements composing the a i and thus can be employed more advantageously sembly. Figure 2 refers to across-sectional view .30 than-various types of Paper 010111- The of the solvent recovery car along the line 2--2 '5 sirable high rate of circulation is attained by Similar numerals refer tosimilar parts through means of the e Said we being of out the drawings. I the type'deemed safe for use with ekplosive gas Referring t Figure 1,, t numem'l denotes mixtures. -As shown, the gases passing through an insulated powder container, said container the filter enter the blower and passtherethrough. preferably being constructed of welded metal and After leaving t e blower. the yi ed is mounted on h so that facil tran fer of separated into predetermined portions, one porthe wd r, together t it contents, e tionbeing passed directly to the heater I0, whereefl t whenever t is deemed desirab1e p p as the remainder. is passed through the condenser, erably, th inner part of the gontaine is com 40 II, and thence through the cyclone separator, l2. structed of stainles t l, because h material Separation or division of the' gas from the blower P rmits the construction of inner surfaces which is effect-ed by means of the Valves dampers. are smooth, and to which particles cannot cling. h being manipulated to attain any The outer surfaces of the carmay be constructed ed f Puring its passage throughsthe 0 of galvanized metal. Insulation may be eflected s the temperature of t s p t of th dryby means of a number of well-known insulating s medium-is cooled sufficiently teceuse 0on4 mat rial la l h proved t very densation of at-least part of thesolvent vapors tractlve for this purpose. This insulate'dfwelded plslent- Further 60 8. is effected, whelf'the metal container, is provided with a screen, 2, said already cooled gases are passed into the cooled screen being adapted td support or retain the '50 ne separator. This latter element i p rpowder being treated while permitting passage of tlcularly effective with respect to the separation the treating medium therethrough. The powder of entrained solventv droplets. The solvent conis introduced intothe container by means of densed passes down -throughthe line l3, which is the openings '3, said openings beingprovided with designed to P v n es pe of s, nd th n lids which may be positioned readily and which in passes to storage. The residual gases exit from .the car atv a locus which is at an appreciable the top of'the separator and pass into the line at a point immediately before the heater, l0, and

behind the valve, It. The passage of part of the From the heater, the gases pass to the top of the powder container, and the circulation described above is repeated.

The details of construction of thepowder car are shown in Fig. 2, wherein the numeral l1 refers to the cover of the car. Said cover is preferably composed of two metallic layers, with a layer of insulating material thereinbetween. This cover merely rests over the insulated side walls, 22, of the car, and forms a vapor-tight which is formed by cooperation of the lip of the cover with the curved member, 23. It will be noted that'the liquid seal is entirely outside the car. This feature is advantageous because it prevents the introduction of water into the system as a result of evaporation of some of the water in the seal. N0 permanent connections or fastenings between the cover and the side walls of the car are employed, the weight of the cover I being sufllcient per se to maintain a closed system. Thus, if accidental ignition of thef powder or gases occurs, the cover is displaced so that the possibility of high pressure being created within the system is greatly reduced. Consequently,;accidental ignition of the contents is usually characterized only by burningyrather than by explosion'or detonation. The members, l9, are employed for removal of the cover.

The cover is providedwith quick opening lids,

I 5, which are made vaporor gas-tight by means of the liquid s'eal, l6. Beneath the cover l1 in theregion below opening 4 is the baffle 20. This member is provided with sf, multiplicity of perforations, and serves as a means for distributing the incoming gas over the entire bed of powder being treated, so that said gas may diffuse through the entire powder bed. Waterunion therewith by means of the liquid seal, l8,

- words, variations in solvent composition of the sprays, 2!, are provided for wetting down the powder at the end of the solvent recover treatment, in case it is desired to remove the powder at the end of said treatment.

The assembly described in the foregoing is employed for the recovery of solvent from smokeless powder in the following manner. Freshly grained or green-smokeless powder is loaded into distance from the place where the solvent recovery process is to be effected. During the loading operation, the major portion of the solvent vapors evolved-may be condensed by passing them 'in' contact with cooling coils. After the charge of the green powder has been introduced into the car,'the various openings of the car are closed and then it is moved from the graining area to the solvent recovery area by meansof a dinghy or other suitable engine provided for hauling such cars when they are superimposedq n a chassis as described hereinbefore. This ortable feature of the car is important because of the fact that it avoids concentration of large quantities of smokeless powder and explosive gas mixtures. The loaded car is then placed in proper position in the solvent recovery area and attachment of the line 5 in the proper position is made. The lids, l5, have already been clamped in a tight position and the water seal has been made. Likewise, attachment at the base of the car is made for the exit vent is continued until potentially all of the solsolvent content of the gases entering the car can be controlled accurately without difliculty.

These conditions may be ,varied so that practically any set of factors considered desirable during the various stages of the operation can be obtained. The length of time of treatment will vary according to the size of the powder grains, their composition, the conditions obtaining during treatment, etc. I l 1 The foregoing apparatus is particularly useful for the efilcient removal of volatile solvent from newly made grains of smokeless powder because it permits control of the solvent vapor content of the medium surrounding the powder and the temperature of this medium as well as thatof the powder. As a result, .the rate of removal of the solvent can be controlled so that when subjected to the treatment, the dimensions of the grain will change uniformly, and controlled shrinkage will be achieved when the solventis removed therefrom. In addition, it is adapted for use in processes involving what may be considered a high rate of circulation of the drying medium, this feature being particularly advantageous in view of the fact that a high flow of the drying medium is conducive to the production of a uniform lot of powder. In other powder are reduced to a minium.

It will be understood that the utility of the present assembly is not limited to the recovery of solvent from freshly-granulated or green smokeless powder. Instead, it may also be employed for the steps employed in the finishing of smokeless powders. These steps usually include preliminary air drying, water drying, and a liminary air drying, it is necessary only to disconnect the pipe at the base of the powder car. employing the resulting opening for introduction of air, and closing the valve into the condenser so that this unit as well as the separator is cut out or the system. As a result, air at room a temperature comes into the piping, passes and through the powder bed, the moist air leavins the car at the exit resulting when the piping was disconnected. For the -water-drying step, it is necessary only to provide an inlet and outlet for hot water of the desired temperature. and to plug the opening at the base of the car. Final air drying of the powder maybe effected in the manner described above for the preliminary air drying treatment.

It will be understood that the assembly described herein is not limited to the use of one powder car. Instead two or more,cars may be attached in parallel to the system, it being essential only that the various parts 01 the assem-- bly be designed to yield the desired flow and temperature'conditions. In such cases it is possible to recover simultaneously the solvent from a plurality of batches of powder while preventing the concentration of an unduly large quan- 393,340, filed May 14, 1941 and issued as U. S.

. Patent No. 2,349,249.

It will be apparent to those skilled in the smokeless powder art that the foregoing description permits of variations, without departing from the spirit or scope thereof. We in-. tend, therefore, to be limited only in accordance I with the following claims.

we claim:

l. A transferable, insulated container adapted for use in the recovery of solvent from smoke less powder, said container comprising an unsecured, removable cover in sealed relationship with the walls thereof, at least one unsecured but vapor-tight lid in said cover, an adit for the introduction of the drying medium into the container, said adit being located in the cover, a

screen for supporting a bed of powder within the container, means for distributing said drying medium over the entire bed of powder, an aperture toward the base of said container for thevexit of said drying medium, and means for removing the powder from the container at the completion of the treatment.

2.. A transferable, insulated container adapted for use in the recovery of-solvent from smokeless powder, said container comprising an unsecured, removable cover in sealed relationship with the walls thereof, at leastone unsecured but vapor"- tight lid in said cover, an adit for the introduction or the drying medium into the container, said adit being located in the cover, a screen for supporting a bed of powder within the container, means for distributing said drying medium over the entire bed of powder, an aperture toward the base of said container for the exit of said drying medium, means for removing the powder from the container at the completion of the treatment, and means for introducing water in the form of sprays into said container.

WALTER A. DEW.

BILL H. MACKEY. RICHARD G. WOODBRIDGE, Jr; 

